High Exposure To Motor Oil Increases Chances Of Developing Arthritis

Occupational exposure to mineral oils, in particular hydraulic or motoroil, increases the risk of developing rheumatoid arthritis by 30%.These are the results of a study published today in Arthritis Research& Therapy.

Berit Sverdrup and Lars Alfredsson, from the Karolinska Institutetin Stockhom, Sweden, and colleagues selected a group of patientsdiagnosed with rheumatoid arthritis (RA) between May 1996 and December2003. They matched these patients with people of the same age, genderand residential area, who acted as controls. Shortly after they hadbeen diagnosed with RA, the patients were asked to complete aquestionnaire regarding occupational exposure to different types ofmineral oils, such as cutting oil, motor oil, form oil, hydraulic oiland asphalt. The same questionnaire was sent to controls.

In total, the study included 1419 cases and 1674 controls. Onlymen reported high occupational exposure to oil, mostly motor andhydraulic oil. A group of 135 men diagnosed with RA and reporting highexposure, as well as 132 matching controls, was retained for furtherstudy.

Sverdrup et al.'s results show that men highly exposed to motoror hydraulic oil have a 30% higher risk of developing RA than unexposedmen. Exposure only increased the risk of developing 'rheumatoid factorpositive' (RF+) rheumatoid arthritis, a more severe form of RA. Itdidn't increase the risk of developing rheumatoid factor negative (RF-)rheumatoid arthritis. Exposure to oil is also linked to a 60% increasedrisk of developing 'anti-citrulline positive' (anti-CP+) rheumatoidarthritis, another type of the disease.

This study confirms results found in animals - exposure to mineral oilhad been shown to induce arthritis in rats -- and raises questionsregarding exposure to other environmental or occupational agents, suchas infectious agents that contain molecules that may activate theimmune system in similar ways as mineral oils, and a possible link witharthritis.